|Locale||Wellington region, New Zealand|
|Ridership||4,461,000 per annum (2011–12)|
Greater Wellington Regional Council (stations)
|Rolling stock||FP/FT class "Matangi" EMUs|
|Track gauge||1,067 mm (3 ft 6 in)|
|Electrification||1600 V DC overhead|
Metlink's Kapiti Line is the electrified southern portion of the North Island Main Trunk Railway between New Zealand's capital city, Wellington, and Waikanae on the Kapiti Coast, operated by Transdev Wellington on behalf of Greater Wellington Regional Council. Trains run frequently every day, with stops at 16 stations. Until 2011 it was known as the Paraparaumu Line.
The Kapiti Line was constructed by the Wellington and Manawatu Railway Company as part of its line between Wellington and Longburn, south of Palmerston North. It was built by a group of Wellington businessmen frustrated with the indecision of the government about the construction of a west coast route out of Wellington.
Construction of the line began in September 1882 and followed a circuitous, steep route via Johnsonville. It was opened to Plimmerton in October 1885 and completed on 3 November 1886. The final spike was driven just north of Paraparaumu, at Otaihanga.
The government acquired the Wellington and Manawatu Railway Company on the 7 December 1908 and incorporated it into its national network as the southern portion of the North Island Main Trunk line.
Deviation and electrification
In 1928, work began on a deviation to avoid the difficult section of the line between Wellington and Tawa through Johnsonville. The deviation required the construction of two significant tunnels between Kaiwharawhara and Tawa. It opened as a single track line to freight on 24 July 1935 and as a double track line to passengers on 19 June 1937. The Wellington to Johnsonville section was retained as the Johnsonville Line.
Electrification from Wellington to Paekakariki was completed on 24 July 1940, avoiding the smoke nuisance in the new deviation's lengthy second tunnel, and providing extra tractive effort on the Paekakariki Hill between Pukerua Bay and Paekakariki. Paekakariki became a major station where long-distance trains swapped from steam (later diesel) to electric motive power and became the northern terminus of the commuter line for many years. Electrification was extended to Paraparaumu on 7 May 1983 and to Waikanae on 20 February 2011.
The Manawatu Railway Company railway when first constructed was a single track railway with crossing loops at principal stations to allow opposing trains to pass. In the 1920s the need for extra train services on the line was recognised, both to increase the tonnage of goods trains and to allow more frequent suburban passenger services. To increase the number of trains that the line could carry, duplication and electrification of the line along with other improvements, such as curve easements, was planned and progressed in stages.
The first section of track duplicated was the Tawa Flat deviation. Completed in 1935, it provided double track from Wellington to Tawa Flat (now Tawa), and bypasses the steep 1 in 36 grades from Wellington to Ngaio Railway Station on the Johnsonville Line.
The section from Plimmerton to South Junction (a little north of Muri Station at the top of the Paekakariki Hill) and from North Junction (at the northern portal of northern Paekakariki tunnel) to Paekakariki was completed in 1940. The difficult single track section between South and North Junctions that passed through five short single track tunnels was left as single track. A proposal that the tunnels on the section between South and North Junctions be replaced with a single double track tunnel has been considered but has not so far been approved.
As part of the Plimmerton to Paekakariki duplication, a Westinghouse three-wire (two feed and one return) Centralised Train Control (CTC) system was installed in 1940; to control trains from Wellington. It was the first CTC system in New Zealand and the first outside the United States of America. This avoided the need for two new signal boxes at the North and South junctions and the need with "tablet" working to continuously man five stations (Tawa, Porirua, Paremata, Plimmerton and Pukerua Bay); so requiring 19 men for traffic working. CTC working applied between Paekakariki and Plimmerton on 25 February, Plimmerton and Paremata on 30 June and Tawa to Porirua on 4 December 1940; giving full traffic control from Wellington to Paekakariki (as Wellington to Tawa was double tracked).
Further duplication was delayed in the 1940s but continued in the 1950s with the completion of the Tawa to Porirua section on 15 December 1957.
Double track from Porirua to Mana was opened on 7 November 1960. Harbour reclamation allowed mostly straight track with the line no longer following the curves of the shoreline bays north of Porirua. A new station and bridge at Paremata were required. The Mana to Plimmerton section was opened on 16 October 1961.
In conjunction with the extension of electrification to Paraparaumu in March 1983, double track was extended from Paekakariki to McKays Crossing on 5 December 1993. The section between McKays Crossing and Paraparaumu, built across a peat swamp, remained single track. Extension of double track from McKays Crossing to a junction south of the Waikanae River bridge was completed in February 2011 to coincide with the extension of electrification to Waikanae.
From electrification in 1940 until the 1980s, the majority of commuter services on the line were operated by DM/D electric multiple units, with some carriage trains hauled by ED and EW electric locomotives, particularly at peak periods. ED and EW locomotives also hauled freight trains over this section until the tunnels between Pukerua Bay and Paekakariki were lowered in 1967 and DA diesel locomotives could be used into Wellington.
From 1982 the new EM/ET electric multiple units were delivered. They had been ordered to replace the wooden carriage trains hauled by electric locomotives on commuter services and largely displaced the DM/D units on the Paraparaumu Line.
By the 1980s, the ED and EW electric locomotives were not required for either freight trains or for commuter trains. They were retired due to age and lack of use, the EDs by 1981 and the EWs by 1988. From 2010 the introduction of the Matangi EMUs provided extra passenger capacity, and enabled the remaining DM/D EMUs to be withdrawn in 2012. A second batch of Matangi EMUs was then ordered to replace the EM/ET EMUs (rather than reconditioning them).
A proposal to extend the electrification to Waikanae was approved by the Greater Wellington Regional Council on 8 May 2007. This project included the double tracking of the single track line between MacKays Crossing (between Paekakariki and Paraparaumu) as far as the rail underbridge and river bridge south of Waikanae. The $90 million project started in December 2008, and was completed in 2011, with the first commuter trains to Waikanae on 20 February. Completion of the project was delayed to 2011 to minimise commuter disruption by working in the quiet end-of-year holiday period, according to ONTRACK program director David Gordon. The project involved 50 workers and 20 machines installing 600 traction poles in eight or nine metre deep holes, and laying 30 km of rail and 30,000 sleepers. The project allows commuter services from Waikanae every 15 minutes at peak travel times but more commonly every 30 minutes. The new Matangi electric multiple units were used on the Kapiti Line from mid-2011. Paraparaumu and Waikanae stations were upgraded at a cost of more than $1 million each. Upgrading Waikanae station rather than moving it south of Elizabeth Street or providing a road underpass was criticised locally, as frequent closing of the Elizabeth Street level crossing south of the station (which connected to State Highway through the town) could increase traffic congestion in Waikanae. However this has since been alleviated by the opening of the Kapiti Expressway which has moved the main road west and out of the centre of Waikanae itself.
Ten traction substations along the line take electricity from Wellington Electricity or Electra's 11,000-volt distribution network and transform and rectify it to 1500-volt direct current for the overhead traction lines. The substations are located at Wellington, Kaiwharawhara, Glenside, Paremata, Mana, Pukerua Bay, Paekakariki, Raumati, Lindale and Waikanae. Also along the line are two "cross-tie" substations at Ngauranga and Tawa, which provide a switching function but don't have transformers or rectifiers.
Public road-rail crossings have warning lights and barriers, and some are now fitted with automatically locking pedestrian gates to prevent use while alarms are operating.
Proposals for new stations at Raumati, between MacKays Crossing and Paraparaumu, and Lindale, north of Paraparaumu near Otaihanga, were on hold, to be reconsidered after 2010, as it was claimed that there were problems affecting a station at Raumati (the provision of access to SH 1 and park-and-ride facilities) and an unstable hillside behind the line.
The 2013 Review and Draft 2014 Review of the Wellington Regional Public Transport Plan confirmed that building additional stations on the Kapiti Line at Raumati and Lindale was no longer recommended, with the cost of new stations outweighing the benefits. The detailed analysis for Raumati (which was a "viability benchmark" for other new stations) said that the modelled peak-hour patronage needed to be about 300 new passengers to justify a new station, and that most Raumati users would have switched from Paraparaumu Station. Network extensions beyond the current Metlink rail operation limits would be by "shuttles or non-electrified services" running to Wellington.
Further extension of the electrification 15 km north from Waikanae to Otaki remains a possibility. A group known as "Save Kapiti" is actively campaigning for the extension. The Otaki Community Board also supports the extension of electrification. Provision has been made during road earthworks north of Waikanae for a future crossing loop between Peka Peka and Otaki. In 2012 the Greater Wellington Regional Council investigated extension of the electrification with Matangi trains north of Waikanae to Otaki (estimated cost $30 million for the Otaki project) and north of Upper Hutt to a new station at Timberlea.
In March 2014 the GWRC said that electrification to Otaki was estimated to cost $115 million to $135 million and was too costly for the number of new passengers it would attract (approximately 250 new passengers). Because the trip would take over an hour, new trains with toilets would be required. As an alternative to electrification, it was suggested that diesel multiple units could be used on services north of Waikanae. This could be a "final nail in the coffin" for the under threat Capital Connection service from Wellington to Palmerston North, which also stops at Otaki. During the 2017 general election, the Green Party proposed extending electrification to Otaki as an alternative to the Northern Corridor extension from Pekapeka.
Proposed infrastructure upgrades include sleeper replacement in tunnels, stabilisation of high risk slopes and renewal of one bridge with timber elements. To cater for freight trains with more frequent passenger trains, there will be a new freight loop at Plimmerton or an improved loop at Porirua (2021/2022; $11.09 million); and Plimmerton will get a high capacity train turn-back facility (2021; $12.8 million). Power supply upgrades will allow more long (8 car) trains (2020; $10.1 million). 
The section between Pukerua Bay and Paekakariki (known as the North-South Junction) may also be double tracked or replaced by a less steep deviation during the first half of the 21st century, although the present proposal is to daylight only the northernmost (No. 7) tunnel which is through rock, and have double track north from there.
- "Wellington Metropolitan Rail 2011/12 Annual Report" (PDF). Greater Wellington Regional Council. 30 June 2012. Retrieved 23 March 2013.
- New Zealand Railway and Tramway Atlas, fourth edition, edited by John Yonge (Essex: Quail Map Company, 1993), 15-16.
- "Metlink - Kapiti Line". Greater Wellington Regional Council.
- "Metlink, January 2011". January 2011.
- Churchman & Hurst 1991, p. 164.
- Churchman & Hurst 1991, pp. 5,6.
- Parsons 2010, pp. 85,86.
- Churchman & Hurst 1991, p. 168.
- Bruce Murray and David Parsons: Rails through the Valley: The story of the construction and use of the railway lines through Tawa (2008, Tawa Historical Society) ISBN 978-0-473-14410-4
- Changes to the Railway Line through Porirua City. Porirua City Council. Accessed 4 September 2016.
- Heine 2000, p. 146.
- Hoy 1970, pp. 70,71.
- Parsons 2010, p. 200.
- Kapiti Observer 18 January 2010 pp8,9
- Kapiti Observer 7 December 2009 page 3
- "Safety upgrade confirmed for high-risk Wellington railway crossing". Stuff (Fairfax). 24 April 2018.
- The Dominion Post, 15 April 2008, page A5 "Railway station plans go on hold"
- metlink wellington bus, train, ferry public transport timetables: Metlink News - Issue 5, April 2008
- Greater Wellington - Kapiti Coast railway upgrade details revealed Archived 14 October 2008 at the Wayback Machine
- Nigel Wilson. "Raumati Station Now". Retrieved 23 February 2011.
- Draft Wellington Regional Public Transport Plan, April 2014 p 58
- "Protests dominate rail opening". More FM Horowhenua. 20 February 2011. Retrieved 24 February 2011.
- "Is Rail the Answer? And if so what is the Question?". Ann Chapman. Retrieved 11 November 2011.
- Kapiti Observer 18 January 2010 page 7
- Forbes, Michael (24 November 2012). "Electric extension for trains". The Dominion Post. Wellington. p. A2.
- "Rail electrification to Otaki too costly". Stuff/Fairfax. 8 March 2014.
- "Greens suggest extending electric rail services and commuter trains". Scoop.co.nz. 18 February 2019. Retrieved 9 March 2019.
- Wellington Timetable Changes and Infrastructure Upgrades by Bruce Taylor in The New Zealand Railway Observer June-July 2018 No 349 Volume 75 No 2, pages 62,63
- Terry McDavitt, et al., Proposed Western Corridor Plan: Hearing Subcommittee's Report (Greater Wellington Regional Council, 8 March 2006), 51-4.
- Churchman, Geoffrey B; Hurst, Tony (2001) [1990, 1991]. The Railways of New Zealand: A Journey through History (Second ed.). Transpress New Zealand. ISBN 0-908876-20-3.
- Parsons, David (2010). Wellington’s Railway: Colonial Steam to Matangi. Wellington: New Zealand Railway & Locomotive Society. ISBN 978-0-908573-88-2.
- Heine, Richard W. (2000). Semaphore to CTC: Signalling and train working in New Zealand, 1863-1993. Wellington: New Zealand Railway & Locomotive Society. ISBN 0-908573-76-6.
- Hoy, D G (1970). Rails out of the Capital. Wellington: New Zealand Railway and Locomotive Society. pp. 18–37.
- Auckland-Wellington Express between Porirua and Paremata, c1932
- Photo of Paraparaumu station and commuter parking
- Photos of Takapu Road station
- Photos of Redwood station
- Photos of Tawa station
- Photos of Linden station
- Ontrack: Kapiti Line upgrade project 2009-11
- "Kapiti Line upgrades (2009-2011)". KiwiRail. Retrieved 19 February 2012.
- "Wellington power supply upgrades (2009-2011)". KiwiRail. Retrieved 19 February 2012.
- "Wellington Stations upgrade (2009-2010)". KiwiRail. Retrieved 19 February 2012.